1. Field of the Invention
The present subject matter relates generally to radiation detection devices, and in particular to compact scintillation radiation detector ensembles that enable detection, identification and azimuth location of a radiation source in a single embodiment.
2. Related Art
The United States government has identified a vital need of law enforcement, first responder and military staff responsible for detecting and responding to radiological threats to the United States to advance the state of the art of available omni-directional radiation detection devices, such as radiation portals and hand-held devices which are sensitive enough to detect many threats, but lack the capability to rapidly determine the location of the radiation source. This problem is complicated by the fact that the terrestrial environment of concern includes significant naturally occurring radioactive material (NORM) and legitimate medical and industrial sources, which camouflage a threat source. Additionally the threat source will often be present in a scatter rich environment further masking the direction and energy of the source. The current information provided may be ambiguous and inadequate in both routine inspection and live threat response scenarios given that the main goal is to find the radiation source or sources quickly to determine the risk level and the appropriate response. It is also possible for a strong benign source to mask a relatively weaker hazardous source in a nearby location. Pertinent information could facilitate sound management of these tense situations, including whether there are one or multiple sources of interest, the azimuth relative to the detector of a gamma source, the location of this source, and the identity of the source. This information must be acquired quickly, so that it may be immediately communicated to the responsible command centers.
Currently available radiation detection and measurement equipment cover a wide range of specific tasks such as isotope identification in a hand-held package and personal radiation locators. However, these devices depend on observing the variation in response intensity as the sensor is moved closer or further from the source. Other devices, often designated gamma cameras or pinhole cameras, accurately locate a gamma source when pointed in the direction of the emissions, but these devices include quite heavy collimation and because of their limited field of view, and are of greatest value only after the threat is originally detected by devices such as those noted above.
Still other devices, known as Compton cameras, while capable of gamma ray azimuth detection, cannot meet the above requirements. Compton cameras work by measuring the track of scintillation resulting from interactions between the incident gamma rays and material in different sections of the detector. The radiation source azimuth can be calculated by backward extension of the track. This approach provides a line that will include the location of the source and provides sensitivity for weak gamma-ray sources compared to non-imaging systems. However, Compton cameras currently are laboratory devices too large and cumbersome for use as set forth above.